1. Technical Field
The present invention relates to end effectors for robot arms, and more particularly to a device for driving mechanical griping jaws to grip articles.
2. Description of Related Art
With the progress of technology, robot arms have been increasingly widely used in various working occasions for replacing manual operation. Especially, in poor working environments, the use of robot arms helps to reduce the risk of process accidents and to protect workers from health threats. For instance, robot arms are perfect to perform welding operation can generate gases, high temperature and blaze that may otherwise hurt workers' respiratory system, burn workers' skin and cause accelerated aging of workers' eyes.
In practical applications of robot arms, the use of end effectors that are designed for specific physical functions is necessary to generate desired physical effects. For example, an end effector designed for operating a gripper to grip an article and moving the article to a different place can provide the physical effect of displacement.
The conventional grippers typically use parts like gears and racks to drive their griping jaws but provide no guiding structure for the movement of the griping jaws. Such a gripper grips or releases an article only depending on making its plural griping jaws come close to each other or leave away from each other by means of gears and racks. However, transmission realized by gears and racks tends to lack precision in terms of positioning the griping jaw. Besides, since the griping jaws are not properly guided, they are likely to move under external force, increasing the risk of errors and falls during griping operation.
Additionally, there are swing links designed for control griping jaws in known grippers. However, such a gripper has its gripping level changing with the distance among its griping jaws, and this makes its gripping operation difficult, especially when gripping thin workpieces. There are also grippers using horizontal swing links to control griping jaws thereof, but they similarly have the problem that the gripping level can change with the distance among the griping jaws. For addressing this problem, a wedge hook has been developed for grippers by whom an external force moving in the axial direction can drive the griping jaws to move in the redial direction. Since the redial movement of the griping jaws is realized by push among their ramps, the problem that the gripping level changes with the distance among the griping jaws can be eliminated. However, such a configuration works on a component of the axial movement that drives the redial movement, so the force applied to make the axial movement has to be greater than the force applied to make the redial movement, and the griping force applied by the gripping jaws is necessarily smaller than the force applied axially. This causes waste of energy that is used to achieve the axial force application.